Brake control apparatus

ABSTRACT

Brake control apparatus for use in a braking system in which an input force from an input member is applied to brake applying means through a lever in the control apparatus, the lever controlling valves in a brake fluid circuit. A substantial proportion of the input force is absorbed by a spring and only the remaining portion of the input force acts on the lever to actuate the brakes. The apparatus includes deceleration sensing means adapted to apply a force to the lever in opposition to the input force. The opposition force is substantially proportional to the deceleration of a wheel controlled by the brake circuit, when the deceleration of the wheel exceeds a predetermined value.

United States atent [111 BJLMA Taft Dec. 25, 1973 [54] BRAKE CONTROLAPPARATUS 3,542,167 11/1970 Wilson 303/21 R [75] Inventor: PhilipAugustus Taft, Solihull,

England Primary Examiner-George E. A. Halvosa Assistant ExaminerEdwardR. Kazenske [73] Assignee: G rling Limited, South Yardley, Attmey Imirie& Smiley Birmingham, England [21] Appl' 169,697 Brake control apparatusfor use in a braking system in which an input force from an input memberis applied [30] F i li i P i i Data to brake applying means through alever in the control Aug 14 1970 Great Britain 39 209/70 apparatus, thelever controlling valves in a brake fluid circuit. A substantialproportion of the input force is [52] Us. Cl l 303/21 F 303/24 Rabsorbed by a spring and only the remaining portion [51] Int Cl" 8/06 ofthe input force acts on the lever to actuate the [58] Field R 24 BBbrakes. The apparatus includes deceleration sensing 305/21 21 1825/1 81means adapted to apply a force to the lever in opposition to the inputforce. The opposition force is sub- [56] References Cited stantiallyproportional to the deceleration of a wheel controlled by the brakecircuit, when the deceleration UNITED STATES PATENTS of the wheelexceeds a predetermined value. 3,608,982 9/1971 Inada et a1 188/181 A3,199,927 8/1965 Bidlack et a1. 303/21 F 7 Claims, 4 Drawing Figures 7349 I I I0 9 8 I l 4 l2 7 1 5 29 ll 7 27 28 30 77 25 r37 E 88 33 4 T q 3I 47 39 ll l 3 2 4 7 J 46 K F// f V 42 43 4'4 P TENIED UECZS 197s 3. 78l. 064

SHEET 2 BF 3 IFIg 2 BRAKE CONTROL APPARATUS This invention relates toimprovements in brake con- .trol apparatus for use in a braking systemof the kind in which an input force from an input member is applied tobrake applying means through a lever, and deceleration responsive meansare adapted to apply to the lever in opposition to the input force aforce substan tially proportional to the deceleration of a wheelcontrolled by a brake circuit, when the deceleration of the braked wheelexceeds a predetermined value.

Hitherto, when brake control apparatus of the kind set foth is in use, aforce is applied to the lever by the brake applying means in oppositionto the input force to provide a reaction or feel on the input member,normally a pedal, in proportion to the magnitude of the brakeapplication.

According to our invention in brake control apparatus of the kind setforth for a braking system the input force is applied to the leverthrough a compression spring which absorbs a substantial proportion ofthe input force, and the remaining proportion of the input force acts onthe lever to actuate the brake applying means.

The brake control apparatus may be used to control the supply of highpressure hydraulic fluid from a high pressure source, conveniently anhydraulic accumulator or pump, to a wheel brake circuit. In such anarrangement the lever is located within a chamber in a housing connectedto the brake circuit through a port in the wall of the housing. A firstnormally open valve controlling communication between the chamber and areservoir for the high pressure source, and a second normally closedvalve controlling communication between the high pressure source and thechamber, are coupled to the lever. When the lever is moved angularlywith respect to the housing by the application of the input force, thefirst valve is closed, and the second valve is opened to allow highpressure fluid to flow from the high pressure source to the brakecircuit through the chamber.

In operation the input force acts at one end of the lever to move thelever angularly through a first distance about its connection with thesecond valve thereby closing the first valve and, thereafter, furthermovement of the said one end of the lever in the same direction througha second distance causes the lever to pivot about its connection withthe first valve, which is located between the said one end of the leverand the second valve, to open the second valve. Thus during the movementthrough the first distance the lever acts as a lever of the third order,and during its movement through the second distance the lever acts as alever of the first order.

The deceleration responsive means acts on the end of the lever oppositeto the said one end at a position outwardly from the connection betweenthe lever and the second valve and in a direction opposite to thedirection in which the input force is applied to the lever.

Preferably the deceleration responsive means comprises asolenoid-operated member which moves through a relatively short distanceto move the lever angularly about its connection with the input memberto close the second valve and open the first when the deceleration ofthe wheel controlled by the brake circuit exceeds a predetermined value.

One embodiment of our invention is illustrated in the accompanyingdrawings in which:

FIG. 1 is an end view of brake control apparatus, in the form of a unitfor connection to separate braking circuits of an hydraulic brakingsystem;

FIG. 2 is a view of the opposite end of the brake contro apparatus shownin FIG. 1;

FIG. 3 is a section on the line 33 of FIG. 1; and

FIG. 4 is a section on the line 44 of FIG. 2.

In the brake control unit illustrated in the drawings 1 is a housingassembly including two longitudinally extending substantially closedchambers 2 which are separated from each other by a longitudinallyextending partition (not shown). Each chamber 2 accommodates alongitudinally extending rigid non-resilient lever 3, and the levers 3are located in spaced parallel side-byside relationship in the chambers2. The upper end of each lever 3 is enlarged and is fixed with a borethrough which is inserted one end of a piston rod 4 working through aplug 5 which closes the outer end of a blind lateral passage 6traversing the chamber 2 in which that lever is accommodated. Thepassages 6 are parallel with each other and a seal 7 at the inner end ofeach plug prevents hydraulic fluid leaking from the chambers 2 throughthe passages. Each piston rod 4 carries a piston 8 working in theportion of the passage on the outer side of the chamber 2, and a spring9 abuts against the piston 8 to hold a collar 10 slidable on the pistonrod 4 in engagement with the adjacent end of the lever 3. The end of thepiston rod 4 which projects from the side of the lever 3 remote from theplug 5 is screwthreaded and carries a nut 11 engaging with an adjacentface of the lever 3. A lock nut 12 is screwed on to the free end of thepiston rod 4, and a Washer 13 interposed between the nuts 11 and 12forms an abutment for one end ofa compression return spring 14 engagingwith the closed end of the passage 6.

A transversely extending balance bar 15 of channel section housed withina transverse recess in the housing assembly 1 is formed adjacent to theopposite ends of its web 16 with a pair of depressions 17 in which theouter ends of the piston rods 4 are received. The web of the bar 15 isformed at substantially the mid-point in its length with an opening 18in which is fixedly secured the open end of a fitting 19 of thimbleoutline which projects into a recess continuous with the recess in whichthe balance bar is located. The recesses which accommodate the balancebar 15 and the thimble 19 are closed by means of a closure cap 20.

An input member in the form of a push-rod 21 extends through alignedopenings in the cap 20 and the thimble l9 and, at its inner end, isguided in a through bore 22 in the housing and parallel with thepassages 6. A screw 23 forming a stop for the inner end of the push-rod21 is secured into the end of the bore 22 remote from the thimble.

The outer end of the push rod 21 is coupled to a brake-applying member,for example a pedal (not shown). A strong compression return spring 24acts between an abutment collar on the push-rod 21 and the closure cap20, and a similar compression spring 25 of lesser strength acts betweenthe inner end of the thimble 19 and an abutment collar 25a on thepush-rod 21 on the inboard side of the closure cap 20. In theinoperative position shown in the drawings the springs 24 and 25 holdthe abutment collar in engagement with the inner face of the cap 20, andthere is a substantial clearance between the inner end of the push-rod21 and the stop screw 23.

The wall of the housing assembly 1 on the side of the chambers 2 remotefrom the balance beam is provided with two aligned unions 26 forconnection to a reservoir for supplying hydraulic fluid to a highpressure source, for example a pump. Each union 26 communicates with oneof the chambers 2 and incorporates an axial bore 27 provided at anintermediate point in its length with an annular shoulder 28 of whichthe innermost radial face defines a seating for a first valve member 29which works in the bore 27 and is of fluted or ribbed form for the wholeof its axial length.

Each valve member 29 is coupled to its respective lever 3 by means of atransverse pin 30 which is fixed in the valve member 29 and received inan axial slot 31 in the lever 2.

A second pair of unions 32 are located in the wall of the housing 1 atpositions below the unions 26. Each union 32 provides communicationbetween a source of hydraulic fluid under pressure, for example the highpressure pump or an hydraulic accumulator supplied by the pump, and oneof the chambers 2. Each union 32 incorporates an axial bore 33 providedat an intermediate point in its length with an annular shoulder 34 ofwhich the innermost radial face defines a seating for the inner end of asecond valve member 35 of fluted section which works in the bore 33.Each of the second valve members 35 is coupled through an extension 36to the inner closed end of a valve spool 37 which works in a bore 38 inthe wall of the housing 1 opposite to the union 32. A compression spring39 acting between the closed inner end of the spool 37 and a threadedplug 40 secured into the outer end of the bore 38 normally holds itsrespective second valve member 35 in engagement with the seating 34 tocut off communication between the source of high pressure fluid and thechamber 2.

Each second valve member 35 is pivotally connected to a respective lever3 at a point on the lever 3 spaced from its connection with the firstvalve 29 by a transverse pin 41 which is fixed in the extension 36.

Each lever 3 adjacent to its free end is coupled to means sensitive todeceleration of a braked wheel.

As illustrated each deceleration sensitive means comprises a solenoidcoil 42 located in a recess in the wall of the housing incorporating theunions 26 and 32. Each solenoid coil 42 surrounds a magnetic core-piece43 which, at its inner end, projects into a respective chamber 2 and isprovided in its inner end with a bore 44 in which is clamped a rod 45.The rod 45 is coupled to one lever 3 by means of a pin 46 in the rod 45which is received in an axial slot 47 in the lever 3.

When installed in a braking system each chamber 2 of the unit isconnected to the wheel brakes of separate brake circuits, through outletconnections 48 and 49, and the solenoids 42 are connected to amplifiermeans 50 for amplifying electrical signals produced by sensor means 51which sense the deceleration of the wheels controlled by the brakes ofthe separate circuits.

In the inoperative position the valve members 35 are urged intoengagement with the seating 34 by means of the springs 39 and the returnsprings 14 25 and 24 hold the levers 3 in retracted positions in whichthe first valve members 29 are held away from their seatings 28. Thusthe chambers 2 are both in communication with the reservoir for the highpressure source.

In the normal operation of the brake, depression of the brake pedaladvances the push rod 21 in the bore 22 against the force of thecompression springs 24 and 25. A substantial proportion of the loadapplied to the pedal is taken in compressing the spring 24 and the rateof the spring 24 is chosen to give satisfactory pedal feelcharacteristics. The remainder of the load is used in compressing thespring 25 so that, at the termination of the advance movement of thepush rod 21, the spring 25 applies to the balance beam 15 a forcesufficient to advance the pistons 8 and piston rods 4 axially andsimultaneously in the passages 6 to actuate the valve members 29 and 35in a manner and sequence to be described hereinafter. At the terminationof the advance movement of the push rod 21, the rod engages with thescrew 23 which forms a stop preventing the system from being overloaded.

As the balance beam advances the pistons 8 and piston rods 4, the returnsprings 14 are compressed, and the levers 3 are moved angularly in acounterclockwise direction with reference to FIG. 3 about the pivotalconnections with the extensions 36 as fulcrums. The levers thus act aslevers of the third order. This angular movement of the levers 3 causethe first valve members 29 to engage with their seatings 28 and cut offcommunication between the reservoir and the chambers 2, through thepassages 27. After the valve members 29 have engaged with the seatings28 further angular movement of the levers 3 in the same direction causethe levers to move angularly about the pivotal connections with thevalve members 29 as fulcrums and move the second valve members 35 awayfrom the seatings 34 against the force of the springs 39. The leversthus act as levers of the first order. Hydraulic fluid under pressure isthen admitted into the chambers 2 through the passage 33 in the unions32 and is delivered to the separate brake circuits through the outletconnections, 48.

The high pressure fluid in the chambers 2 acts on the pistons 8 to applyto the rods 4 forces in direction opposing the input forces from thebalance bar 15. With the assistance of the forces in the return springs14 the pistons 8 and the balance bar 15 move in the opposite directioninto a neutral position against the force of the compression spring 25.This permits the valve members 35 to engage with their seatings 34 andcut out the supply of high pressure fluid into the chambers 2. Thepush-rod 21 remains in the advanced position and the reaction of thehigh pressure fluid on the pistons 8 is not transmitted to the brakepedal.

When the deceleration of a braked wheel of one of the brake circuitsexceeds a predetermined value, the corresponding solenoid 42 isenergised to retract the magnetic core piece 43 and draw that end of thelever coupled to that core piece 43 through the rod 45 towards thesolenoid. This causes the lever to act as lever of the first order andfulcrum about its pivotal connection with the extension 36 of the valvemember 35. The upper end of the lever 3 moves towards the balance bar 15sliding the collar 10 along the piston rod 4 against the force in thecompression spring 9, which is compressed. Simultaneously the firstvalve member 29 is moved away from its seating 28 to permit highpressure fluid supplied to the brake of that braking circuit to berelieved and returned to the reservoir through the chamber 2.

The pressure in the chamber 2 which was previously acting on the piston8 is thus relieved so that the piston 8 and the piston rod 4 advancesautomatically into its original advanced position and the balance bartilts about its engagements with the outer ends of the piston rods 4.

When the deceleration of the braked wheel drops below the saidpredetermined value the solenoid is deenergised and the force in thespring 9 urges that end of the lever 3 axially to move the lever 3angularly in a direction to urge the valve member 29 against its seating28 and urge the valve member 35 away from its seating 34 as dewcribedabove. Thereafter the operation of the appratus is repeated as describedabove.

The sequence of relieving the braking pressure when the deceleration ofa braked wheel exceeds a predetermined value as described above, maytake place independently, simultaneously or sequentially for each of theseparate brake circuits supplied from the separate chambers when thedeceleration of a wheel or wheels of the separate circuits exceeds thesaid predetermined values.

The sizes of the valves 29 and 35 are chosen so that strokes of thepistons 8 and the loads applied thereto are small. Variation in the loadin the spring due to changes in the axial positions of the pistons 8 isvery small and represent only a small proportion of the total loadapplied to the push-rod 21. Thus such variations in the load of thespring 25 will not be felt by the driver of the vehicle when depressingthe brake pedal.

Our invention has the advantage that one unit controls simultaneouslythe braking characteristics of two separate braking circuits. Normalpedal reaction or feel is obtained on each and every brake applicationand, under conditions in which the braking effort applied to a wheel isrelieved, such relief of braking effort is not translated to the driver.

The provision of the strong spring 24 enables the rate of that spring tobe chosen to meet the requirements of any particular driver.

The provision of solenoid operated deceleration sensing means enablesadvantage to be taken of a minimum energy requirement and this in turn,enables the solenoid to be designed to give minimum inductive delay andmaximum response. Furthermore the short travel requirement of thesolenoid 42 required to effect relief of the braking pressure enablesthe solenoid to be designed with low hysteresis characteristics.

The arrangements of the pistons 8 and the valve members obviate thenecessity for providing superfine finishes on hydraulic bores, therebyreducing the cost of a unit to a minimum.

I claim:

1. Brake control apparatus for a vehicle braking system incorporating afluid brake circuit, said apparatus comprising a housing in which thereis a chamber, a port in said housing communicating with said chamber andbeing adapted for connection to said brake circuit, a first normallyopen valve for controlling fluid flow between said chamber and a fluidreservoir, a second normally closed valve for controlling fluid flowbetween said chamber and a high pressure source, a lever pivotallymounted in said chamber, angular movement of said lever relative to saidhousing causing said first valve to close and subsequently said secondvalve to open whereby high pressure fluid from the high pres sure sourcecan flow through said chamber and through said port to said brakecircuit, a first spring, a pedaloperated input member operativeto applyan input force to said lever through said first spring to cause angularmovement of the lever, a second spring operative to absorb a substantialproportion of the pedal-loading on the input member whereby said inputforce is only a minor proportion of the pedal-loading, and meansresponsive to the deceleration of a braked wheel operative to apply tosaid lever a force in opposition to said input force when thedeceleration of the wheel exceeds a predetermined value.

2. A brake control appratus as claimed in claim 1 wherein saiddeceleration responsive means comprises a solenoid operated member whichin operation is movable through a relatively short distance to move saidlever angularly in a direction to close said second valve andsubsequently open said first valve when the deceleration of the wheelcontrolled by said brake circuit exceeds said predetermined value.

3. A brake control apparatus as claimed in claim 1, comprising a housingin which there are two separate sealed chambers, a pair of levers onepivotally mounted and located in each of said chambers, a pair of inputrods one connected to each of said levers, a balance beam operative toact on both of said input rods, the first spring operative to transmitan input force to said balance beam and thence to said input rods andsaid levers to operate first and second valves associated with eachchamber.

4. A brake control apparatus as claimed in claim 3 wherein each of saidchambers is in communication with a separate brake circuit.

5. A brake control apparatus as claimed in claim 1 wherein there is amechanical connection between said lever and said first valve, amechanical connection between said lever and said second valve, and saidinput force acts at one end of said lever causing said lever to moveangularly through a first distance about said mechanical connection withsaid second valve thereby closing said first valve, and, thereafter,further movement of said lever in the same direction through a seconddistance causing said lever to pivot about said mechanical connectionwith said first valve thereby opening said second valve.

6. A brake control apparatus as claimed in claim 5 wherein said firstvalve is located between said one end of said lever and said secondvalve, said lever acting as a lever of the third order during itsmovement through said first distance, and acting as a lever of the firstorder during its movement through said second distance.

7. A brake control apparatus as claimed in claim 5 wherein saiddeceleration responsive means acts on the end of said lever opposite tosaid one end in a direction opposite to the direction of the input forceapplied to said lever.

1. Brake control apparatus for a vehicle braking system incorporating afluid brake circuit, said apparatus comprising a housing in which thereis a chamber, a port in said housing communicating with said chamber andbeing adapted for connection to said brake circuit, a first normallyopen valve for controlling fluid flow between said chamber and a fluidreservoir, a second normally closed valve for controlling fluid flowbetween said chamber and a high pressure source, a lever pivotallymounted in said chamber, angular movement of said lever relative to saidhousing causing said first valve to close and subsequently said secondvalve to open whereby high pressure fluid from the high pressure sourcecan flow through said chamber and through said port to said brakecircuit, a first spring, a pedal-operated input member operative toapply an input force to said lever through said first spring to causeangular movement of the lever, a second spring operative to absorb asubstantial proportion of the pedal-loading on the input member wherebysaid input force is only a minor proportion of the pedal-loading, andmeans responsive to the deceleration of a braked wheel operative toapply to said lever a force in opposition to said input force when thedeceleration of the wheel exceeds a predetermined value.
 2. A brakecontrol appratus as claimed in claim 1 wherein said decelerationresponsive means comprises a solenoid operated member which in operationis movable through a relatively short distance to move said leverangularly in a direction to close said second valve and subsequentlyopen said first valve when the deceleration of the wheel controlled bysaid brake circuit exceeds said predetermined value.
 3. A brake controlapparatus as claimed in claim 1, comprising a housing in which there aretwo separate sealed chambers, a pair of levers one pivotally mounted andlocated in each of said chambers, a pair of input rods one connected toeach of said levers, a balance beam operative to act on both of saidinput rods, the first spring operative to transmit an input force tosaid balance beam and thence to said input rods and said levers tooperate first and second valves associated with each chamber.
 4. A brakecontrol apparatus as claimed in claim 3 wherein each of said chambers isin communication with a separate brake circuit.
 5. A brake controlapparatus as claimed in claim 1 wherein there is a mechanical connectionbetween said lever and said first valve, a mechanical connection betweensaid lever and said second valve, and said input force acts at one endof said lever causing said lever to move angularly through a firstdistance about said mechanical connection with said second valve therebyclosing said first valve, and, thereafter, further movement of saidlever in the same direction through a second distance causing said leverto pivot about said mechanical connection with said first valve therebyopening said second valve.
 6. A brake control apparatus as claimed inclaim 5 wherein said first valve is located between said one end of saidlever and said second valve, said lever acting as a lever of the thirdorder during its movement through said first distance, and acting as alever of the first order during its movement through said seconddistance.
 7. A brake control apparatus as claimed in claim 5 whereinsaid deceleration responsive means acts on the end of said leveropposite to said one end in a direction opposite to the direction of theinput force applied to said lever.